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Sunday 8.4.2012

Sunday 8.4.2012. Comparison of the fills 2488 and 2489.

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Sunday 8.4.2012

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  1. Sunday 8.4.2012

  2. Comparison of the fills 2488 and 2489 • 264 bunches, separation in Atlas and CMS (to 75% and 95% respectively). It seems to indicate a larger activity in the horizontal plane when the beam are separated and in particular for the larger separation (corresponding to 75% of the peak luminosity).

  3. Sunday Morning and Afternoon • 7:17 – 11:34 Fill 2489 stable beams (264 bunches) • Atlas and CMS separated to 95% peak luminosity and stay with constant offset for 1st hour • 8:24 Atlas and CMS at 100% for 2nd hour • Separated during 3rd hour • At peak lumi during 4th hour • 12 pb-1delivered luminosity • 12:30 – 13:30 Left jaw blocked on TCSG.5L3B1. Collimator jaw lost motor steps and stayed blocked. Piquet restored the resolver positions. To be analyzed on Tuesday. • 14:54 – 16:10 Fill 2490 (264 bunches) stable beams • Average intensity 1.5e11 per bunch • Initial luminosity: 11x1032cm-2s-1 • Losses not higher than 10-15% of dump thresholds all along the cycle (below 10% on RS 1.3s during collisions BP). • 5 pb-1delivered luminosity

  4. Fill 2491 (624 bunches) • 18:20 – 4:37 Fill 2491 stable beams (624 bunches) • Average intensity1.4e11 ppb • Initial luminosity: 24x1032cm-2s-1 • 60 pb-1delivered luminosity Intensity B1 Intensity B2

  5. Fill 2491 (624 bunches), cont. • BLM at warning level (>30% of threshold) • During SQUEEZE: TCLA point 7 • During ADJUST: MQWA point 7 (D5 and E5 L7) • During stable beams (19:17) at the BGI • Some vacuum activity (4L8 and 6R7)

  6. Fill 2492 • 4:50 Ramping down ALICE solenoid and dipole (+compensators) • Masking interlocks related to IR2 spectrometer • send frequency trim of 13Hz to center the orbit. The RMS was worse than usually due to Alice spectrometer OFF, corrected with Feedback only. • Steering transfer line TI8 • 12 bunches and 36 do not have the same averagebunch intensity • When preparing the ramp, the TCDQ beam 1 did not take the settings due to ref mismatch. The setting in the frontend was correct, but not the reading. Applying the already charged settings again from the collimator application. Solved the problem. • 7:32 beams dumped during squeeze by BLM at TCLA.D6L7 RS 1.3 sec (losses on B2).

  7. Others • Back to the working point 0.312/0.322 for both beams when going in collision (increase by 2E-3 both planes). • Deployed functions to reduce the chromaticity by -1 unit both planes both beams at the beginning of the collisions BP (from 2 to 1 unit). • ADT phase shift functions during the squeeze adapted: • go from positive to negative values with a required jump from +179 to -180 this year (after having removed 1 turn of delay). The jump has been programmed to last 100 ms. Unfortunately this generates according to the attached logging intermediate points, which can make the system unstable for a brief moment of time. • Problems with FIDEL (17:07), chromaticity changing at injection • Restarted server CMW-DIP-LHC-EXP on cs-ccr-cmw1 to get he lumi values published properly (3:45).

  8. Others cont. • Vacuum activity at BGI (19:17 - ) • Mariusz: “I see strange behavior of HV on one of BGIs (beam 1, vertical detector). Will investigate, for the moment I shut it down. It has started between 19 and 20 during the first fill with 624 bunches. It is correlated with a vacuum spike. Horizontal detector, working with the same operational voltages, has no problems. Nevertheless I have lowered voltages on it. To be investigated. Of course there was no gas injection performed during this time. The profiled I have observed had large tails, similar as during the scrubbing run last year.”

  9. Planning

  10. Planning • Friday till Monday the morning meeting will be at 9:00 • Tuesday 8:30 summary of the week • 3 fills and 20 hours with 624b, 840b, 1092b, 1380b (intensity/lumi related problems)

  11. Intensity ramp-up • 2-3 fills and 4-6 hours with 48b, 84b, 264b and 624b (cycle validation) • 3 fills and 20 hours with 840b, 1092b, 1380b (intensity/lumi related problems) • MP checklists after 84b, 624b, 840b, 1092 bunches • Regular MP checklists every two weeks when operating with 1380b

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